1. Field of the Invention
The instant invention relates to open celled electrically semi-conducting and conducting ceramic networks and methods for their production. An open celled, electrically semi-conducting ceramic network of the instant invention is useful in a variety of applications, for example: (1) as a plate of an electrostatic precipitator, particularly useful because it can be operated in a corrosive environment, (2) as an electrically energized mixer and preheater for gases and liquids, (3) as an electrical resistor, and (4) as a particulate trap in the exhaust system of a diesel engine.
2. Description of the Prior Art
Open celled ceramics, their use as catalyst supports, and methods for producing them, are disclosed in U.S. Pat. No. 4,083,905. The reference discloses fabrication of the ceramic supports by flocking an organic sponge with wood or textile fibers, impregnating the flocked sponge with an organic solvent dispersion containing alumina, a silicone resin and a flux, and sintering the impregnated organic sponge at a high temperature to vitrify the ceramic and burn out the sponge.
U.S. Pat. No. 4,040,998 discloses an improvement on the invention of the above-described patent. The improvement involves the use of a suitable detergent to enable the production of an aqueous dispersion of the alumina, silicone resin and flux. The open celled ceramic networks disclosed in both of these references are non-conducting, electrically.
U.S. Pat. Nos. 3,046,328 and 3,247,132 both disclose electrically conducting glass seals which expand during firing and, therefore, are porous. However, the seals are confined during firing so that they form a closed cell structure which is an effective gas seal.